Alarm circuit of ultrasonic liquid level sensor

Abstract

The utility model discloses an alarm circuit of an ultrasonic liquid level sensor. The alarm circuit comprises a sampling circuit, a filter circuit, a differential amplification circuit and an alarm circuit, the sampling circuit comprises an operational amplifier U1, a pin 1 of the operational amplifier U1 is electrically connected with one end of a resistor R3 and one end of a capacitor C1, a pin 3 of the operational amplifier U1 is electrically connected with the positive electrode of a diode D1, a pin 2 of the operational amplifier U1 is electrically connected with one end of a resistor R4, and the other end of the resistor R4 is electrically connected with one end of a resistor R2 and one end of a resistor R5. Collected information is filtered through the filter circuit, and high-frequency noise in the circuit is suppressed in cooperation with the differential amplification circuit, so that the circuit stability is improved, the anti-interference effect is achieved, the false alarm condition can be effectively reduced, and the stability in the using process is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to ultrasonic liquid level sensor technical field especially relates to a kind of alarm circuit of ultrasonic liquid level sensor. BACKGROUND

[0002] The main function of the alarm circuit of ultrasonic liquid level sensor is to detect the liquid level and issue an alarm. When the liquid level reaches the preset warning line, the circuit will trigger an alarm to notify relevant personnel to take measures. The alarm circuit in the prior art has poor anti-electromagnetic interference effect, and its circuit is easily disturbed by electromagnetic noise, leading to false alarm and misjudgment by workers. Therefore, the present application provides an alarm circuit of ultrasonic liquid level sensor. SUMMARY

[0003] The utility model discloses an alarm circuit of ultrasonic liquid level sensor to solve the shortcomings in the prior art.

[0004] To achieve the above object, the utility model adopts the following technical scheme:

[0005] An alarm circuit of ultrasonic liquid level sensor includes a sampling circuit, a filter circuit, a differential amplifier circuit and an alarm circuit.

[0006] The sampling circuit includes an operational amplifier U1. One end of resistor R3 and one end of capacitor C1 are electrically connected to pin 1 of the operational amplifier U1. The positive electrode of diode D1 is electrically connected to pin 3 of the operational amplifier U1. One end of resistor R4 is electrically connected to pin 2 of the operational amplifier U1. One end of resistor R2 and one end of resistor R5 are electrically connected to the other end of resistor R4. The other end of resistor R5 is grounded. One end of resistor R1 is electrically connected to the other end of resistor R2. The other end of resistor R2 is electrically connected to the other end of resistor R3. One end of resistor R7 is electrically connected to pin 4 of the operational amplifier U1. One end of resistor R6 is electrically connected to the other end of resistor R7. The other end of resistor R6 is grounded.

[0007] The alarm circuit includes a buzzer L. One end of the buzzer L is electrically connected to one end of an indicator lamp LED. The other end of the indicator lamp LED is electrically connected to one end of resistor R8. The other end of resistor R8 is electrically connected to the other end of the buzzer L. One end of the buzzer L is electrically connected to the collector of a triode Q1. One end of resistor R10 is electrically connected to the emitter of the triode Q1. The other end of resistor R10 is grounded. The positive electrode of diode D2 is electrically connected to the base of the triode Q1. One end of resistor R9 is electrically connected to the positive electrode of diode D2.

[0008] Preferably, the filter circuit comprises an operational amplifier U2, one end of a resistor R11 and one end of a capacitor C2 are electrically connected to pin 1 of the operational amplifier U2, the other end of the capacitor C2 is electrically connected to one end of a resistor R19, the other end of the resistor R19 is electrically connected to pin 3 of the operational amplifier U2, one end of a resistor R12 is electrically connected to pin 2 of the operational amplifier U2, one end of a capacitor C4 is electrically connected to the other end of the resistor R12, one end of a resistor R20 is electrically connected to the other end of the capacitor C4, the other end of the resistor R20 is electrically connected to pin 3 of the operational amplifier U2, the other end of the resistor R12 and one end of the capacitor C4 are grounded, and the other end of the resistor R11 is electrically connected to pin 5 of the operational amplifier U1.

[0009] Preferably, the differential amplification circuit comprises a transistor Q2 and a transistor Q3, the base of the transistor Q2 is electrically connected to pin 3 of the operational amplifier U2, one end of a resistor R13 is electrically connected to the collector of the transistor Q2, one end of a capacitor C3 and the positive electrode of a diode D3 are electrically connected to the emitter of the transistor Q2, one end of a resistor R18 and one end of a resistor R17 are electrically connected to the negative electrode of the diode D3, the other end of the resistor R18 is grounded, one end of a resistor R15 is electrically connected to the other end of the resistor R17, one end of a resistor R14 is electrically connected to the other end of the capacitor C3, the emitter of the transistor Q3 is electrically connected to one end of the resistor R17 and the negative electrode of the diode D3, one end of a resistor R16 is electrically connected to the collector of the transistor Q3, the other end of the resistor R16, the other end of the resistor R14, the other end of the resistor R13 and the other end of the resistor R15 are electrically connected to a high level VCC, the base of the transistor Q3 is electrically connected to the other end of the resistor R9, and the emitter of the transistor Q3 is electrically connected to one end of the resistor R18.

[0010] Preferably, the resistor R1 is a sampling resistor, the capacitor C1 is a sample-and-hold capacitor, and the resistor R5 is a feedback resistor for feeding back sampled data.

[0011] Preferably, the buzzer L and the indicator lamp LED are synchronously operated.

[0012] Preferably, the resistor R19 and the resistor R10 constitute a gain adjustment network for controlling a closed-loop amplification multiple, and the capacitor C4 is used for suppressing high-frequency oscillation.

[0013] Preferably, the transistor Q2 and the transistor Q3 constitute a symmetric differential pair, the capacitor C3 and the resistor R14 constitute a frequency compensation network for suppressing high-frequency noise and improving circuit stability.

[0014] Compared with the prior art, the utility model has the advantages of:

[0015] The utility model discloses a filter circuit to the information of collection carries out the filter processing, and cooperate difference amplifier circuit to restrain the high frequency noise in the circuit, thereby improve the circuit stability, reach the effect of anti -interference, can reduce the false alarm situation, improve the stability in the use process. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A block diagram of the alarm circuit of the ultrasonic liquid level sensor is provided in the utility model;

[0017] Figure 2 A circuit diagram of the alarm circuit of the ultrasonic liquid level sensor is provided in the utility model;

[0018] Figure 3 A circuit diagram of the filter circuit in the alarm circuit of the ultrasonic liquid level sensor is provided in the utility model;

[0019] Figure 4 A circuit diagram of the difference amplifier circuit in the alarm circuit of the ultrasonic liquid level sensor is provided in the utility model. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all the embodiments.

[0021] REFERENCE Figures 1-4 An alarm circuit of an ultrasonic liquid level sensor, comprising a sampling circuit, a filter circuit, a difference amplifier circuit and an alarm circuit;

[0022] The sampling circuit comprises an operational amplifier U1, one end of a resistor R3 and one end of a capacitor C1 are electrically connected to a pin 1 of the operational amplifier U1, a positive electrode of a diode D1 is electrically connected to a pin 3 of the operational amplifier U1, one end of a resistor R4 is electrically connected to a pin 2 of the operational amplifier U1, one end of a resistor R2 and one end of a resistor R5 are electrically connected to the other end of the resistor R4, the other end of the resistor R5 is grounded, one end of a resistor R1 is electrically connected to the other end of the resistor R2, the other end of the resistor R2 and the other end of the resistor R3 are electrically connected, one end of a resistor R7 is electrically connected to a pin 4 of the operational amplifier U1, one end of a resistor R6 is electrically connected to the other end of the resistor R7, and the other end of the resistor R6 is grounded, wherein the resistor R1 is a sampling resistor, the capacitor C1 is a sampling holding capacitor, and the resistor R5 is a feedback resistor for feeding back the sampled data;

[0023] The alarm circuit comprises a buzzer L, one end of the buzzer L is electrically connected with one end of an indicating lamp LED, the other end of the indicating lamp LED is electrically connected with one end of a resistor R8, the other end of the resistor R8 is electrically connected with the other end of the buzzer L, one end of the buzzer L is electrically connected with the collector of a triode Q1, one end of a resistor R10 is electrically connected with the emitter of the triode Q1, the other end of the resistor R10 is grounded, the base of the triode Q1 is electrically connected with the anode of a diode D2, the anode of the diode D2 is electrically connected with one end of a resistor R9, and the other end of the resistor R9 is electrically connected with the other end of the resistor R8.

[0024] The filter circuit comprises an operational amplifier U2, one end of a resistor R11 and one end of a capacitor C2 are electrically connected with pin 1 of the operational amplifier U2, one end of a resistor R19 is electrically connected with the other end of the capacitor C2, the other end of the resistor R19 is electrically connected with pin 3 of the operational amplifier U2, one end of a resistor R12 is electrically connected with pin 2 of the operational amplifier U2, one end of a capacitor C4 is electrically connected with the other end of the resistor R12, one end of a resistor R20 is electrically connected with the other end of the capacitor C4, the other end of the resistor R20 is electrically connected with pin 3 of the operational amplifier U2, the other end of the resistor R12 and one end of the capacitor C4 are grounded, and the other end of the resistor R11 is electrically connected with pin 5 of the operational amplifier U1, wherein the resistor R19 and the resistor R10 constitute a gain adjustment network for controlling the closed-loop amplification multiple, and the capacitor C4 is used for inhibiting high-frequency oscillation.

[0025] The differential amplification circuit comprises a triode Q2 and a triode Q3, the base of the triode Q2 is electrically connected with pin 3 of the operational amplifier U2, one end of a resistor R13 is electrically connected with the collector of the triode Q2, one end of a capacitor C3 and the anode of a diode D3 are electrically connected with the emitter of the triode Q2, one end of a resistor R18 and one end of a resistor R17 are electrically connected with the cathode of the diode D3, the other end of the resistor R18 is grounded, one end of a resistor R15 is electrically connected with the other end of the resistor R17, one end of a resistor R14 is electrically connected with the other end of the capacitor C3, the emitter of the triode Q3 is electrically connected with one end of the resistor R17 and the cathode of the diode D3, one end of a resistor R16 is electrically connected with the collector of the triode Q3, the other end of the resistor R16, the other end of the resistor R14, the other end of the resistor R13 and the other end of the resistor R15 are electrically connected with a high level VCC, the base of the triode Q3 is electrically connected with the other end of the resistor R9, and the emitter of the triode Q3 is electrically connected with one end of the resistor R18, wherein the triode Q2 and the triode Q3 constitute a symmetrical differential pair, the capacitor C3 and the resistor R14 constitute a frequency compensation network for inhibiting high-frequency noise and improving the stability of the circuit, the collected information is filtered by the filter circuit, the high-frequency noise in the circuit is inhibited by cooperating with the differential amplification circuit, the stability of the circuit is improved, the effect of anti-interference is achieved, the false alarm condition can be reduced, and the stability in the use process is improved.

[0026] Working principle: when using, the liquid level signal is collected through the resistance R1 and fed back to the operational amplifier U1 through the resistance R5 for amplification, the amplified signal is transmitted to the filter circuit, the high frequency signal enters the capacitor C2 and resistance R19 network for attenuation, the capacitor C4 is short-circuited at high frequency, and the resistance R20 reduces the high frequency gain, thereby inhibiting the noise of the overall circuit, the processed electrical signal enters the differential amplifier circuit, the input signal is applied to the triode Q2 and triode Q3, the triode Q2 and triode Q3 current synchronous change approaches zero, effectively inhibiting common mode interference, at the same time, the capacitor C3 and resistance R14 constitute a frequency compensation network to inhibit high frequency noise in the signal, improve the stability of the circuit, and achieve the effect of anti-interference;

[0027] The processed signal enters the alarm circuit, when applied to the input end of the resistance R9, the current flows through the resistance R9, is limited, and then is injected into the base of the triode Q1 through the diode D2, so that the triode Q1 enters the saturated conduction state, after the triode Q1 is turned on, the power supply voltage forms a loop through the buzzer L, the collector of the triode Q1, the emitter of the triode Q1 and the resistance R10, the buzzer L emits sound, and the indicator lamp LED is turned on at the same time, so as to alarm and remind personnel, the working mode of triggering the buzzer L and the indicator lamp LED after processing the electrical signal can reduce false alarm and improve the stability.

[0028] The above is only the preferred specific implementation mode of the present application, but the protection scope of the present application is not limited to this, any skilled person in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. An alarm circuit for an ultrasonic liquid level sensor, characterized by The sampling circuit, the filtering circuit, the differential amplification circuit and the alarm circuit are included. The sampling circuit includes an operational amplifier U1, one end of a resistor R3 and one end of a capacitor C1 are electrically connected to pin 1 of the operational amplifier U1, the anode of a diode D1 is electrically connected to pin 3 of the operational amplifier U1, one end of a resistor R4 is electrically connected to pin 2 of the operational amplifier U1, one end of a resistor R2 and one end of a resistor R5 are electrically connected to the other end of the resistor R4, the other end of the resistor R5 is grounded, one end of a resistor R1 is electrically connected to the other end of the resistor R2, the other end of the resistor R2 and the other end of the resistor R3 are electrically connected, one end of a resistor R7 is electrically connected to pin 4 of the operational amplifier U1, one end of a resistor R6 is electrically connected to the other end of the resistor R7, and the other end of the resistor R6 is grounded. The alarm circuit includes a buzzer L, one end of the buzzer L is electrically connected to one end of an indicator lamp LED, the other end of the indicator lamp LED is electrically connected to one end of a resistor R8, the other end of the resistor R8 and the other end of the buzzer L are electrically connected, the emitter of a transistor Q1 is electrically connected to one end of the buzzer L, one end of a resistor R10 is electrically connected to the emitter of the transistor Q1, the other end of the resistor R10 is grounded, the anode of a diode D2 is electrically connected to the base of the transistor Q1, and one end of a resistor R9 is electrically connected to the anode of the diode D2.

2. An alarm circuit for an ultrasonic liquid level sensor according to claim 1, wherein The filtering circuit includes an operational amplifier U2, one end of a resistor R11 and one end of a capacitor C2 are electrically connected to pin 1 of the operational amplifier U2, one end of a resistor R19 is electrically connected to the other end of the capacitor C2, the other end of the resistor R19 is electrically connected to pin 3 of the operational amplifier U2, one end of a resistor R12 is electrically connected to pin 2 of the operational amplifier U2, one end of a capacitor C4 is electrically connected to the other end of the resistor R12, one end of a resistor R20 is electrically connected to the other end of the capacitor C4, the other end of the resistor R20 is electrically connected to pin 3 of the operational amplifier U2, the other end of the resistor R12 and one end of the capacitor C4 are grounded, and the other end of the resistor R11 is electrically connected to pin 5 of the operational amplifier U1.

3. An alarm circuit for an ultrasonic liquid level sensor according to claim 2, wherein, The differential amplifier circuit comprises a transistor Q2 and a transistor Q3, the base of the transistor Q2 is electrically connected with pin 3 of the operational amplifier U2, one end of the resistor R13 is electrically connected with the collector of the transistor Q2, one end of the capacitor C3 and the anode of the diode D3 are electrically connected with the emitter of the transistor Q2, one end of the resistor R18 and one end of the resistor R17 are electrically connected with the cathode of the diode D3, the other end of the resistor R18 is grounded, one end of the resistor R15 is electrically connected with the other end of the resistor R17, one end of the resistor R14 is electrically connected with the other end of the capacitor C3, the emitter of the transistor Q3 is electrically connected with one end of the resistor R17 and the cathode of the diode D3, one end of the resistor R16 is electrically connected with the collector of the transistor Q3, the other end of the resistor R16, the other end of the resistor R14, the other end of the resistor R13 and the other end of the resistor R15 are electrically connected with a high level VCC, the base of the transistor Q3 is electrically connected with the other end of the resistor R9, and the emitter of the transistor Q3 is electrically connected with one end of the resistor R18.

4. An alarm circuit for an ultrasonic liquid level sensor according to claim 1, wherein The resistor R1 is a sampling resistor, the capacitor C1 is a sample and hold capacitor, and the resistor R5 is a feedback resistor for feeding back the sampled data.

5. An alarm circuit for an ultrasonic liquid level sensor according to claim 1, wherein The buzzer L works synchronously with the indicator lamp LED.

6. An alarm circuit for an ultrasonic liquid level sensor according to claim 2, wherein The resistor R19 and the resistor R10 constitute a gain adjustment network for controlling the closed-loop amplification multiple, and the capacitor C4 is used for suppressing high-frequency oscillation.

7. An alarm circuit for an ultrasonic liquid level sensor according to claim 3, wherein The transistor Q2 and the transistor Q3 constitute a symmetrical differential pair, the capacitor C3 and the resistor R14 constitute a frequency compensation network for suppressing high-frequency noise and improving the stability of the circuit.

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